Sure the last 8 years has been amazing to bitcoin, and bubbles had damaged a lot in the begining, nowadays the value is much more stable and has a better support, but  prediting bitcoin at 500k dollars its insane, since the more cost bitcoin becomes it loose more and more investors, people wont be able to keep buying forever bitcoin with a price always increasing. At 2020 the bitcoin value should be around 1100-1300 dollars, and we are already  into those, soo at those period maybe 2000 dollars can be achieved, but this is all speculation, otherwise all people would make huge loans just to get inside bitcoin.